Reduce deep nesting of header files

Reduce the number of header files included from other header
files as much as possible without splitting the files. Use forward
declarations where possible. This allows removal of some unnecessary
"#ifndef __ASSEMBLY__" statements.

Also, review the .c and .S files for which header files really need
including and reorder the #include statements alphabetically.

Fixes ARM-software/tf-issues#31

Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e
diff --git a/plat/fvp/bl31_plat_setup.c b/plat/fvp/bl31_plat_setup.c
index 5abe236..aa7b2d8 100644
--- a/plat/fvp/bl31_plat_setup.c
+++ b/plat/fvp/bl31_plat_setup.c
@@ -28,9 +28,13 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <platform.h>
 #include <arch.h>
+#include <bl_common.h>
+#include <bl31.h>
 #include <console.h>
+#include <mmio.h>
+#include <platform.h>
+#include <stddef.h>
 #include "drivers/pwrc/fvp_pwrc.h"
 
 /*******************************************************************************